31-10-16, 08:49 PM
It's either going to be valve noise or cam chain noise. If you put a screwdriver on the valve cover and the other end at your ear you'll be able hear inside the engine and determine if it's valve noise or cam chain noise. Old oil will increase noise from both of them so if you're due an oil change it'd be no harm changing it and that might help. The cam chain tensioner is automatic and can get stuck or can be between adjustment and causes more cam chain noise. Then one day it just disappears because the tensioner advances and takes up the slack. I've heard if you put the bike in gear and push it backwards you can force the tensioner on a notch. Not too sure if it works or not. At 40k I think you're getting into worn out cam chain territory. Some people get way more mileage out of them but mine was worn out at 40k. Try the screwdriver trick first and try and work out where the noise is coming from.